Roche ($RHHBY) is spotlighting another success for its PD-L1 checkpoint drug atezolizumab, with company execs applauding a positive finish in a big mid-stage study in non-small cell lung cancer. The news follows a string of steady pipeline advancements for a drug that has emerged as the pharma giant's biggest single late-stage blockbuster contender.

Roche subsidiary Genentech says that atezo hit the primary endpoint in the study, which recruited 667 patients. That's big compared to most Phase II trials, but Roche and competitors like Merck ($MRK) and Bristol-Myers Squibb ($BMY) have been pouring billions of dollars into the clinical trials for these drugs--there are 11 Phase III studies for atezo underway--as they start to carve out market niches for the most advanced drugs. Just weeks ago Roche announced that it would angle for an early approval for atezo in bladder cancer after seeing promising mid-stage data in that field.

Roche has breakthrough drug designation status from the FDA for atezo in lung cancer, giving the pharma giant a possible inside track on an accelerated approval for this drug.

"We plan to present results at an upcoming medical meeting and will discuss these data as well as results from our other lung cancer studies with health authorities to bring this medicine to patients as quickly as possible,'' said Roche CMO Sandra Horning in a statement.

Investigators are keeping the data under wraps for now, a common ploy as the big companies position themselves to make headlines at upcoming scientific conferences. But the company's announcement noted that atezo was linked to shrinking tumors among advanced patients. And investigators noted that the likelihood of response correlated with the amount of PD-L1 expressed on cancer cells--a potentially key distinguishing factor for this drug.

PD-L1, or Programmed Death Ligand-1, is found on cancer cells. Tumors use PD-L1 to jam a connection with PD-1 and B7.1 connections found on T cells, preventing an immune system attack. Roche and AstraZeneca ($AZN) are engaged in ambitious efforts to get the first PD-L1 drug to the market, while Bristol-Myers and Merck push ahead with Opdivo and Keytruda after winning the first groundbreaking approvals.

This is a crucial campaign for Roche/Genentech. Analysts covering the company have been growing anxious about the paucity of big wins in the pipeline in recent years, enhancing the critical nature of success. The FDA has already indicated its willingness to speed up approvals, particularly in cancer, giving Roche a clear opening. Roche and its partner AbbVie ($ABBV) recently announced that they would hustle an application to the FDA for venetoclax after seeing promising results in a blood cancer study.